Bowhead whales are members of the baleen whale family. Instead of teeth, baleen whales have a series of large, thin plates of baleen or “whalebone” in their mouths. The whales use baleen to strain small plankton, called krill, out of the sea. Krill is their main food. Bowheads are large, blue-black whales. They form white blotches on the lower jaw as they get older. Males can measure up to 20 m in length and weigh up to 70 tonnes. Their name comes from their upper jaw, which is curved upward like a bow. Whalers called bowheads “right” whales because they were slow and they floated when killed, making them the “right” whales to hunt. Bowhead whales were prized catches because they yielded a large amount of blubber, sometimes more than 35 tonnes, and large baleen plates, which could measure up to 4m. In the 19th century, baleen was much sought after because it had many of the same uses that plastic does today.

Distribution

Bowheads are circumpolar in their distribution. They are found in most arctic waters between 55oN and the permanent polar ice pack. Historically, there have been five separate bowhead populations: the Spitsbergen stock, also known as the Greenland whale, found in the far northern Atlantic Ocean; the Davis Strait Stock, in eastern Hudson Bay and Davis Strait; the Hudson Bay stock, found around southern Baffin Island; the Okhotosk Sea Stock, found in northern Russia; and the western Arctic stock, found in the Bering, Chukchi and Beaufort Seas. Bowheads are still found throughout their historical range. The bulk of the world population is concentrated in the Bering, Chukchi and Beaufort Seas.

Historical estimates put the world’s bowhead population at more than 50,000 whales. Of these, 14,000-20,000 were members of the Beaufort Sea stock. Beginning in the 1700s, whalers began hunting some of the bowhead populations. By the mid-19th century, all five bowhead whale populations had been hunted almost to the point of extinction. Very little is known about current bowhead populations outside of the Beaufort stock. The world population is currently estimated at 8,500 bowhead whales. Of these, most belong to the Bering/Chukchi/Beaufort stock. There is evidence that this stock is increasing in size. The Beaufort population has increased from an estimated 4,500 individuals in the late 1970s to an estimated 7,500 in the early 1990s.

Habitat

Ice is the most important factor in the bowhead whale’s environment. The freeze and thaw of the ice dictates the whale’s annual migration. The whales follow the retreating ice north in the summer to feed on the invertebrate blooms of the arctic summer. In the fall they travel south, following the edge of the forming ice to the nutrient-rich waters of Bering Strait. They winter in polynyas (permanently open areas in the ice) and near the edge of the ice pack in the western and central Bering Strait. The ice also offers protection as they hide among ice floes to escape their main predator, the killer whale.

Biology

Female bowheads are larger than males, and are sexually mature when they reach a length of 13.5 metres. Males become mature at a length of 12-13 metres. Bowheads mate in the late winter and calve in the spring 13-14 months later. Females have one calf every three to four years. Calves are weaned when they reach about 9-12 months of age. Bowheads are one of the most vocal baleen whales. They probably use their vocalizations to maintain contact with each other when they migrate.

Limiting Factors

Bowheads, like many whales, are migratory. Their annual cycle of movements leaves them vulnerable to hunting. However, subsistence hunting has not been shown to be a limiting factor. As the Arctic’s natural resources are developed, there is growing concern that oil and gas exploration in the Beaufort Sea will have a dramatic effect on the migration of bowheads. The whales do not appear to mind drilling rigs and other permanent structures. However, the sound vibrations from boats and other machines seem to deter them from an area. This could lead to a later arrival at their summer feeding areas, preventing the whales from gaining enough blubber to survive the winter. This could have an adverse effect on their population.

Protection

Since 1946, bowheads have been protected by the International Whaling Commission. In Canada, bowheads were protected from 1951 to 1982 under the Whaling Convention Act. This act only allowed the harvest of whales for subsistence use by indigenous peoples. In 1979, Canada prohibited the killing of all right whales without a license. Canada withdrew from the International Whaling Commission in 1982 and replaced the Whaling Convention Act with the Cetacean Protection Act (Cetacean is the scientific term for whales). This act allows the Minister of Fisheries to issue licences for Aboriginal people to hunt whales. The Convention on International Trade in Endangered Species (CITES) prohibits the trade of whalebone. COSEWIC designated the bowhead whale as Endangered in 1986 because of scientific uncertainties about their numbers and the possible adverse effects of industry. Using results from more recent surveys, COSEWIC re-assessed the Bering-Chukchi-Beaufort Sea population of bowhead whales that uses NWT waters from Endangered to Special Concern in 2005. In the NWT, bowheads are hunted in the Inuvialuit Settlement Region where one whale can be harvested annually.

Recovery

The Bowhead population in the Beaufort Sea appears to be increasing. The International Whaling Commission manages the western Arctic stock (also called the Bering-Chukchi-Beaufort Sea population) and sets quotas for Alaskan Inuit. More information about bowhead populations is needed. New sonar techniques are being used to count whales and annual sightings are recorded to gain a clearer picture of the population.